The present invention relates to a unit cell for solid electrolyte type fuel cell and a related manufacturing method and, more particularly, to a unit cell for a solid electrolyte type fuel cell with a structure wherein a solid electrolyte is sandwiched between a pair of electrodes, and a related manufacturing method.
In recent years, it has heretofore been proposed to provide a solid electrolyte type fuel cell (hereinafter referred to as SOFC) which is comprised of electric power generating component parts which are configured in a structure wherein a solid oxide electrolyte is sandwiched between two electrodes, i.e. between the a fuel electrode (anode) and an air electrode (cathode) to which hydrogen gas or hydrocarbon gas, such as methane, and oxidizing gas, such as oxygen and air, are supplied, respectively, to produce electric power output. It is to be noted that the component parts such as the fuel electrode, the electrolyte and the air electrode are hereinafter suitably referred to as electric power generating component parts.
Such a SOFC has a high electric power generating efficiency while enabling waste heat to be recaptured and is so highly expected as a third-generation fuel cell.
One of cell structures of such a SOFC involves an electrolyte supporting type cell shown in FIG. 1.
In FIG. 1, an elaborate electrolyte body 12 is prepared by sintering electrolyte material powder at a high density, with upper and lower surfaces thereof being covered with an air electrode 11 and a fuel electrode 10 that are formed by screen printing. Also, in such a cell, the electrolyte body 12 is used as a supporting member.
Further, Japanese Patent Application Laid-Open Publication No. H9-50812 discloses a porous electrode substrate formed of a sintered body of ceramic electrode material powder with pore rates different in a direction along the thickness of the sintered body.
Also, Japanese Patent Application Laid-Open Publication No. 2000-200614 discloses a porous electrode substrate formed of a sintered body of ceramic material powder.
In addition, it has been proposed to provide a cell formed of a porous metallic substrate 1, that serves as a supporting member of electric power generating component parts, i.e. a fuel electrode 10, an electrolyte 12 and an air electrode 11, as shown in FIG. 3, which are formed on the substrate by thermal spraying.
Further, a so-called DLR cell (Plasma Sprayed thin-Film SOFC for reduced Operating Temperature, Fuel Cells Bulletin, pp 597–600, 2000) has also been proposed.
Further, Japanese Patent Application Laid-Open publication No. H7-45297 and Japanese Utility Model Application Laid-Open Publication No. S63-106063 disclose a SOFC which employs a current collecting member such as a Ni-felt separately of electrodes for collecting electric power output produced across a fuel electrode and an air electrode.
Furthermore, it is a usual practice for such SOFC to be utilized under a circumstance wherein multiple cell components are electrically connected in wither series or in parallel and, therefore, it is required to provide a connecting member (hereinafter referred to as I. C. (an interconnector)) for providing electrical connections among respective cell component parts. There are some instances where such I. C. has a current collecting function.
In addition, since the SOFC is so arranged as to allow hydrogen or hydrocarbon fuel gas such as methane to be supplied to the fuel electrode and oxygen or oxidizing gas such as air to be supplied to the air electrode for thereby generating electric power output, there is a need for preparing a member that forms a gas flow passage for introducing gas to the electrode surfaces. There are some instances where the member for forming the gas flow passage has the I. C. function.